Cooling unit for cooling a heat generating component and electronic apparatus having the cooling unit

ABSTRACT

An electronic apparatus comprises a housing for accommodating a heat generating component and a display unit supported by the housing. A heat receiving head thermally connected to the heat generating component is accommodated inside the housing. A heat radiator is disposed in the display unit. A heat receiving head and the heat radiator are connected to each other through a circulating path for circulating cooling medium. The circulating path is provided with an intermediate cooling unit. Before cooling medium heated by heat transfer by the heat receiving head reaches the heat radiator, the intermediate cooling unit forces cooling medium to be cooled.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2000-287691, filed Sep. 21,2000, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a cooling unit for forcing a heatgenerating component like a semiconductor package to be cooled withliquid-like cooling medium and an electronic apparatus provided with thecooling unit, such as a portable computer.

2. Description of the Related Art

An electronic apparatus like a portable computer has a micro processingunit (MPU) for processing multi-media information such as characters,voices and animation. This MPU tends to increase generation of heatduring its operation accompanied by currently increased processing speedand multiple functions. Thus, in order to ensure a stable operation ofthe MPU, it is necessary to intensify heat radiation performance of thisMPU.

Conventionally, a portable computer loaded with a MPU generating a largeamount of heat is equipped with an air-cooling type cooling unit forforcing the MPU to be cooled. This cooling unit has a heat sinkthermally connected to the MPU and an electric fan for supplying coolingair to this heat sink.

In this cooling unit, heat from the MPU is transmitted to the heat sinkand then discharged out of the computer through a flow of cooling air.Therefore, because according to the conventional cooling method, coolingair serves as a cooling medium for depriving the MPU of heat, thecooling performance of the MPU mostly depends on air feeding performanceof the electric fan. If the feeding amount of cooling air is increasedto aim at intensifying cooling performance of the MPU, the rotationamount of the electric fan is increased, so that there is produced sucha problem that a large noise may be produced. Additionally, because inthe portable computer, a housing for incorporating the MPU and electricfan is designed so thin in a compact body, it is difficult to secure aspace for accommodating a large electric fan having an excellent airfeeding performance and an ideal air feeding path inside the housing.

In near future, it is expected that the processing speed of the MPU forthe portable computer will be further accelerated and the MPU willbecome multi-functional, and accompanied by this trend, the heatgeneration of the MPU increases tremendously. Thus, the conventionalforced air-cooling system has a fear that the cooling capacity for theMPU becomes short or reaches its limit.

As a means for improving this, for example, Jpn. Pat. Appln. KOKAIPublication No. 7-142886 has disclosed so-called liquid cooling systememploying liquid having a higher specific heat than air as heattransferring medium.

According to this new cooling system, a heat receiving header connectedto the MPU thermally is disposed inside the housing and a heat radiatingheader is disposed inside the display housing supported by this housing.The heat receiving header and the heat radiating header are connected toeach other through a circulating pipe in which liquid-like coolingmedium flows.

Because according to this cooling system, cooling medium circulatesbetween the heat receiving header and the heat radiating header, heatfrom the MPU is transmitted to the heat receiving header and after that,transferred to the heat radiating header via the cooling medium. Heattransferred to the heat radiating header is discharged to the atmosphereby diffusion by heat conduction to the display housing. For the reason,the heat radiating header is connected thermally to the display housingand the display housing is composed of metallic material havingexcellent heat conductivity.

Therefore, such liquid cooling system is capable of transferring heat ofthe MPU more effectively than the conventional forced air coolingsystem, thereby raising the cooling performance of the MPU.

Meanwhile, heat of the MPU transferred from the heat radiating header tothe display housing is discharged to the atmosphere from the surface ofthe display housing through natural convection and heat radiation. Thus,as the amount of heat transferred to the display housing increases, thesurface temperature of the display housing is raised. As a result, ifuser happens to touch the surface of the display housing whenopening/closing the display housing or carrying the computer, he or shemay feel discomfort or heat.

Further, according to the liquid cooling system, a heat radiating headerinside the display housing is connected to a heat receiving headerinside the housing through a circulating pipe. Thus, if a necessity ofremoving this display housing from the housing occurs to carry outmaintenance on the interior of the display housing, the heat receivingheader thermally connected to the MPU needs to be removed from thehousing temporarily.

However, disassembly of the periphery of such a precision MPU not onlyleads to damage of the MPU but also may make inappropriate thepositional relationship between the heat receiving header and the MPUupon installation of the heat receiving header. Thus, this isunfavorable in terms of maintaining reliability of thermal connectionbetween the MPU and the heat receiving header.

If the MPU is loaded on a place difficult to access like a rear face ofa circuit board, a troublesome work of disassembling the housing andtaking out the circuit board is required. This work can be said to beinappropriate in viewpoint of operation efficiency and therefore, thereis a room for improvement at this point.

BRIEF SUMMARY OF THE INVENTION

A first object of the present invention is to provide a cooling unit andan electronic apparatus capable of preventing a rise in temperature ofthe surface of a display unit.

A second object of the present invention is to provide an electronicapparatus, which allows a second housing to be removed from a firsthousing without releasing thermal connection between a heat receivingportion and a heat generating component and which can bedisassembled/reassembled easily and maintain reliability of heatconduction favorably.

In order to achieve the above-described first object, according to afirst aspect of the present invention, there is provided a cooling unitfor use in an electronic apparatus having a computer main bodycontaining a heat generating component and a display unit supported bythe computer main body, the cooling unit comprising: a heat receivingportion thermally connected to the heat generating component andaccommodated in the computer main body; a heat exchanging portioninstalled on the display unit; circulating means for circulating coolingmedium between the heat receiving portion and the heat exchangingportion, the circulating means having a pipe line for introducingcooling medium heated by the heat receiving portion to the heatexchanging portion; and intermediate cooling means installed in the pipeline, the intermediate cooling means forcing the heated cooling mediumflowing from the heat receiving portion to the heat exchanging portionto be cooled.

Further, in order to achieve the above-described first object, accordingto a second aspect of the present invention, there is provided anelectronic apparatus comprising: a housing containing a heat generatingcomponent; a display unit supported by the housing; a heat receivingportion accommodated in the housing and thermally connected to the heatgenerating component; a heat exchanging portion installed on the displayunit; circulating means for circulating cooling medium between the heatreceiving portion and the heat exchanging portion, the circulating meansbeing disposed throughout the housing and the display unit and having apipe line for introducing cooling medium heated by the heat receivingportion to the heat exchanging portion; and intermediate cooling meansinstalled in the pipe line of the circulating means, the intermediatecooling means forcing the heated cooling medium flowing from the heatreceiving portion to the heat exchanging portion to be cooled.

With such a structure, heat from the heat generating component istransferred to the cooling medium by means of the heat receivingportion. This heat is transmitted to the heat exchanging portion througha flow of the cooling medium. The cooling medium cooled by heat exchangeby means of the heat exchanging portion is returned to the heatreceiving portion and receives heat from the heat generating componentagain. By repeating such a cycle, heat from the heat generatingcomponent is transmitted to the display unit effectively and dischargedto the atmosphere.

The cooling medium heated through heat conduction from the heatreceiving portion is cooled via the intermediate cooling means before itreaches the heat exchanging portion. Thus, the temperature of thecooling medium introduced by the heat exchanging portion can be lowered.Thus, the rise in temperature of the surface of the display unit can besuppressed despite discharging heat from the heat generating componentfrom the display unit, so that a bad influence upon user using theelectronic apparatus can be reduced to such a level having no problem.

In order to achieve the above-described second object, according to athird aspect of the present invention, there is provided an electronicapparatus comprising: a first housing containing a heat generatingcomponent; a second housing, the second housing being journaleddetachably on a rear end of the first housing through a hinge devicehaving a hinge shaft extending in the width direction of the firsthousing and having a rear face which is directed backward of the firsthousing when the second housing is rotated to a posture in which itstands up from the rear end of the first housing; a heat receivingportion accommodated inside the first housing and thermally connected tothe heat generating component; a heat exchanging portion installed onthe second housing, the heat exchanging portion being capable of beingtaken out of the rear face; and circulating means for circulating thecooling medium between the heat receiving portion and the heatexchanging portion, the circulating means comprising a first pipe linefor introducing cooling medium heated by the heat receiving portion tothe heat exchanging portion and a second pipe line for introducingcooling medium cooled by heat exchange by means of the heat exchangingportion to the heat receiving portion, the first and second pipe linesbeing disposed throughout the inside of the first housing and the insideof the second housing via backward of the hinge shaft, the rear face ofthe second housing having at least an opening portion at a positioncorresponding to the first and second pipe lines, the opening portionbeing covered with a removable lid.

With such a structure, heat from the heat generating component istransferred to the cooling medium by means of the heat receivingportion. This heat is transferred to the heat exchanging portion throughthe cooling medium flowing through the first pipe line. The coolingmedium cooled by heat exchange by the heat exchanging portion isreturned to the heat receiving portion through the second pipe line andreceives heat from the heat generating component again. By repeatingsuch a cycle, heat from the heat generating component is transmittedeffectively to the second housing and discharged thereof to theatmosphere.

In order to remove the second housing from the first housing, first, thelid covering the opening portion of the second housing is removed so asto expose the first and second pipe lines introduced to the interior ofthe second housing through the opening portion. Subsequently, the heatexchanging portion is taken out in the direction of the rear face of thesecond housing and the first and second pipe lines continuous to thisheat exchanging portion are taken out of the opening portion.Consequently, with the first and second pipe lines connected to the heatexchanging portion, this heat exchanging portion can be taken out of thesecond housing. Finally, the hinge device is removed from the firsthousing so as to separate the second housing from the first housing.

In order to install the second housing onto the first housing, thesecond housing is installed onto the first housing through the hingedevice. After that, the heat exchanging portion is installed on thesecond housing in the direction of the rear face of the second housing.Next, the first and second pipe lines continuous to the heat exchangingportion are inserted into the second housing through the opening portionand then this opening portion is covered with the lid. As a result, thefirst housing and the second housing are connected to each other and theinstallation of the heat exchanging portion onto the second housing iscompleted.

Consequently, when removing the second housing from the first housing,it is not necessary to release thermal connection between the heatreceiving portion and the heat generating component. Thus, a troublesomework of disassembling or reassembling portions corresponding to the heatgenerating component and heat receiving portion is not required, so thatthe removal of the second housing is facilitated. Further, nounreasonable force is applied to the heat generating component or thepositional relationship between the heat generating component and theheat receiving portion is not changed, thereby making it possible tomaintain reliability of thermal connection between the both.

In order to achieve the above-described second object, according to afourth aspect of the present invention, there is provided an electronicapparatus comprising: a housing accommodating a heat generatingcomponent and being capable of being opened upward; a display unitsupported by the housing; a heat receiving portion accommodated in thehousing and thermally connected to the heat generating component; a heatexchanging portion installed on the display unit; and circulating meansfor circulating cooling medium between the heat receiving portion andthe heat exchanging portion, the circulating means comprising a firstpipe line for introducing cooling medium heated by the heat receivingportion to the heat exchanging portion and a second pipe line forintroducing cooling medium cooled by heat exchange by means of the heatexchanging portion to the heat receiving portion, the first and secondpipe lines being disposed throughout the inside of the housing and theinside of the display unit and being divided to upstream portions anddownstream portions inside the housing, the upstream portions and thedownstream portions being connected detachably through a joint, thejoint having closing means for closing the first and second pipe lineswhen the first and second pipe lines are divided to the upstreamportions and the downstream portions.

With such a structure, heat from the heat generating component istransferred to cooling medium by the heat receiving portion. This heatis transmitted to the heat exchanging portion through the cooling mediumflowing through the first pipe line. Cooling medium cooled by heatexchange by means of the heat exchanging portion is returned to the heatreceiving portion through the second pipe line and receives heat fromthe heat generating component again. By repeating such a cycle, heatfrom the heat generating component is transmitted to the second housingeffectively and discharge thereof to the atmosphere.

In order to remove the second housing from the first housing, the firsthousing is opened upward so as to expose the first and second pipe linesintroduced to the interior of the first housing. Next, the first andsecond pipe lines extending throughout the heat receiving portion andthe heat exchanging portion are divided inside the first housing.Consequently, when removing the second housing having the heatexchanging portion from the first housing, the first and second pipelines make no obstacle and the thermal connection between the heatreceiving portion and the heat generating component does not have to bereleased. As a result, a troublesome work of disassembling/reassemblingportions corresponding to the heat generating component and heatreceiving portion is not required, so that the removal of the secondhousing is facilitated. Further, no unreasonable force is applied to theheat generating component or the positional relationship between theheat generating component and the heat receiving portion is not changed,so that reliability of thermal connection between the both can bemaintained.

Further, if the upstream portions and the downstream portions of thefirst and second pipe lines are separated from each other, the first andsecond pipe lines are automatically closed. Therefore, no cooling mediumleaks from the first and second pipe lines and thus, no special work forsealing the first and second pipe lines is required.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiment of the invention, andtogether with the general description given above and the detaileddescription of the embodiment given below, serve to explain theprinciples of the invention.

FIG. 1 is a perspective view of a portable computer according to a firstembodiment of the present invention;

FIG. 2 is a perspective view of a lid for covering an opening portion ina display housing according to the first embodiment of the presentinvention;

FIG. 3 is a sectional view of the portable computer having aliquid-cooling type cooling unit according to the first embodiment ofthe present invention;

FIG. 4 is a sectional view of the portable computer indicating a secondpipe line insertion path when the display unit is rotated to its openingposition in the first embodiment of the present invention;

FIG. 5 is a sectional view of the portable computer indicating a jointstructure between the computer main body and the display unit accordingto the first embodiment of the present invention;

FIG. 6 is a sectional view of the portable computer indicating thesecond pipe line insertion path when the display unit is rotated to itsclosing position in the first embodiment of the present invention;

FIG. 7 is a sectional view of the portable computer indicating a statein which the lid thereof is removed from the display housing in thefirst embodiment of the present invention;

FIG. 8 is a sectional view showing a positional relationship between aheat receiving head and a semiconductor package in the first embodimentof the present invention;

FIG. 9 is a sectional view of the heat receiving head indicating thestructure of inside of a heat transmitting case in the first embodimentof the present invention;

FIG. 10 is a sectional view of a heat radiator for use in the firstembodiment of the present invention;

FIG. 11 is a sectional view of an intermediate cooling unit indicatingthe positional relationship between a refrigerant path and a cooling airpath in the first embodiment of the present invention;

FIG. 12 is a flow chart showing electric fan control system of the firstembodiment of the present invention;

FIG. 13 is a sectional view of the portable computer indicating a statein which the heat radiator is removed form the display housing in thefirst embodiment of the present invention;

FIG. 14 is a perspective view of the portable computer according to asecond embodiment of the present invention;

FIG. 15 is a perspective view of the portable computer according to athird embodiment of the present invention;

FIG. 16 is a sectional view of the portable computer having a liquidcooling type cooling unit according to a fourth embodiment of thepresent invention;

FIG. 17 is a perspective view of a holder for maintaining an intervalbetween a first pipe line and a second pipe line constant in the fourthembodiment of the present invention;

FIG. 18A is a sectional view of a joint indicating a state in which afirst joint portion and a second joint portion are joined together inthe fourth embodiment of the present invention; and

FIG. 18B is a sectional view of the joint indicating a state in whichthe first joint portion and the second joint portion are separated fromeach other in the fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the first embodiment of the present invention applied to aportable computer will be described with reference to FIGS. 1 to 13.

FIGS. 1 and 3 show a portable computer 1 which is an electronicapparatus mentioned in this specification. The portable computer 1comprises a computer main body 2 and a display unit 3, which issupported by this computer main body 2.

The computer main body 2 has a first housing 4 of synthetic resin. Thefirst housing 4 is a flat box comprising a bottom wall 4 a, an upperwall 4 b, right/left side walls 4 c, a front wall 4 d and a rear wall 4e. The first housing 4 is composed of a base 5 having the bottom wall 4a and a top cover 6 having the upper wall 4 b. The top cover 6 isinstalled detachably to the base 5. Thus, by removing the top cover 6from the base 5, the first housing 4 is opened upward.

A hallow convex portion 8 protruded upward is formed at a rear endportion of the upper wall 4 b of the first housing 4. The convex portion8 is extended in the width direction of the first housing 4 behind akeyboard 9. The convex portion 8 has display supporting portions 10 aand 10 b on both ends thereof. The display supporting portions 10 a and10 b are constructed in the form of a dent open continuously forward,upward and backward of the convex portion 8. The bottom of each of thedisplay supporting portions 10 a and 10 b is located downward of theupper wall 4 b as shown in FIG. 4.

As shown in FIGS. 3 and 4, a circuit board 11 is accommodated inside thefirst housing 4. The circuit board 11 is disposed in parallel to thebottom wall 4 a of the first housing 4. A semiconductor package 12 isinstalled at a left end portion of the top face of the circuit board 11as a heat generating component.

The semiconductor package 12 composes a micro processing unit (MPU),which serves as the center of the portable computer 1. As shown in FIG.8, the semiconductor package 12 includes a rectangular base substrate 13and an IC chip 14 soldered on the top face of this base substrate 13.The base substrate 13 is soldered to the top face of the circuit board11 through plural soldering balls 15. In this kind of the semiconductorpackage 12, its power consumption during operation has been increasedaccompanied by currently intensified processing speed and multiplefunctions, so that heat generation from the IC chip 14 has become solarge that cooling of the chip is required.

As shown in FIGS. 1 and 3, the display unit 3 comprises a displayhousing 17 serving as a second housing and a liquid crystal displaypanel 18 accommodated in this display housing 17. The display housing 17is composed of, for example, synthetic resin material and constructed inthe form of a thin flat box having a front face 20 in which an openingportion 19 is formed and a rear face 21 opposing this front face 20. Theliquid crystal display panel 18 has a display screen (not shown) fordisplaying information such as characters and pictures. This displayscreen is exposed out of the display housing 17 through the openingportion 19.

The display housing 17 has a pair of leg portions 23 a and 23 bprotruded from an end portion thereof. The leg portions 23 a and 23 bare hallow and apart from each other in the width direction of thedisplay housing 17. The leg portions 23 a and 23 b are introduced to thedisplay supporting portions 10 a and 10 b in the first housing 4.

The right leg portion 23 a is supported by the first housing 4 via ahinge device 24. The hinge device 24 comprises a first bracket 25, asecond bracket 26 and a hinge shaft 27. As shown in FIG. 5, the firstbracket 25 is screwed to a top end of plural boss portions 28 extendedupward from the bottom wall 4 a. A rear end portion of the first bracket25 is introduced to inside of the convex portion 8 on the right side ofthe display supporting portion 10 a. As shown in FIG. 4, the secondbracket 26 is screwed to an inside face at the right end of the frontface 20 of the display housing 17. An end portion of the second bracket26 is introduced into inside of the right leg portion 23 a. The hingeshaft 27 is stretched between the rear end portion of the first bracket23 a and the end portion of the second bracket 26 such that it passesthrough a side face of the leg portion 23 a and a side face of thedisplay supporting portion 10 a. For the reason, the hinge shaft 27 isdisposed horizontally along the width direction of the first housing 4and the display housing 17.

An end portion of the hinge shaft 27 is rotatably coupled with the rearend portion of the first bracket 25. The other end portion of the hingeshaft 27 is fixed to the end portion of the second bracket 26. Afriction type brake mechanism (not shown) employing, for example, a wavewasher is built in a joint portion between the hinge shaft 27 and thefirst bracket 25. This brake mechanism limits a free rotation of thehinge shaft 27.

Thus, the display unit 3 is rotatable around the hinge shaft 27. Ifspeaking more in detail, the display unit 3 is supported on the firsthousing 4 rotatably with respect to the hinge shaft 27 from a closingposition in which the same display unit 3 is tilted down so as to coverthe key board 9 to an opening position in which it is raised so as toexpose the key board 9 and the display screen. When the display unit 3is turned to the opening position, the rear face 21 of the displayhousing 17 is directed rearward of the portable computer 1.

As shown in FIG. 3, the portable computer 1 incorporates a liquidcooling-type cooling unit 30 for forcing the semiconductor package 12 tobe cooled. The cooling unit 30 comprises a heat receiving head 31 as aheat receiving portion, a heat radiator 32 as a heat exchanging portionand a circulation path 33 as circulating means.

As shown in FIGS. 8 and 9, the heat receiving head 31 is accommodated inthe first housing 4. This heat receiving head 31 has a heat transmittingcase 34. The heat transmitting case 34 is composed of metal materialhaving an excellent thermal conductivity like aluminum alloy. This heattransmitting case 34 is constructed in the form of a thin flat boxhaving a plane larger than the semiconductor package 12.

The heat transmitting case 34 contains plural guide walls 35 inside. Theguide walls 35 are disposed in parallel to each other with an intervalbetween one and another, so that the inside of the heat transmittingcase 34 is divided to plural refrigerant flow paths 36. The heattransmitting case 34 has a refrigerant intake 37 and a refrigerantoutlet 38. The refrigerant intake 37 is located at an upstream end ofthe refrigerant flow paths 36. The refrigerant outlet 38 is located at adownstream end of the refrigerant flow paths 36.

The heat transmitting case 34 is supported on the top face of thecircuit board 11 via its four corner portions with screws 39. This heattransmitting case 34 opposes the circuit board 11 across thesemi-conductor package 12. A heat transmitting sheet 40 is disposedbetween the central portion on the bottom face of the heat transmittingcase 34 and the IC chip 14 of the semiconductor package 12. The heattransmitting case 34 is pressed against the IC chip 14 through a leafspring 41 so that the heat transmitting sheet 40 is sandwiched betweenthe heat transmitting case 34 and the IC chip 14. Thus, the heattransmitting case 34 is thermally in contact with the IC chip 14 throughthe heat transmitting sheet 40.

As shown in FIGS. 3 and 4, the heat radiator 32 is accommodated insidethe display housing 17. The heat radiator 32 has the first and secondheat radiating plates 43 a and 43 b. The first and second heat radiatingplates 43 a and 43 b are composed of metal material having an excellentthermal conductivity like for example aluminum alloy and havesubstantially the same size as the liquid crystal display panel 18.

As shown in FIG. 10, the first heat radiating plate 43 a and the secondheat radiating plate 43 b are overlaid over each other. The second heatradiating plate 43 b has a concave portion 44, which is open to amatching face with the first heat radiating plate 43 a. The concaveportion 44 is formed meanderingly on substantially entire surface of thesecond heat radiating plate 43 b. The concave portion 44 forms aradiated heat path 45 with the matching face with the first heatradiating plate 43 a. The radiated heat path 45 has a refrigerant intake46 and a refrigerant outlet 47. The refrigerant intake 46 is open to theleft leg portion 23 b inside the display housing 17. The refrigerantoutlet 47 is open to the right leg portion 23 a inside the displayhousing 17. Thus, the refrigerant intake 46 and the refrigerant outlet47 are apart from each other in the width direction of the displayhousing 17.

The aforementioned circulation path 33 has a first pipe line 50 and asecond pipe line 51. The first and second pipe lines 50 and 51 arecomposed of metallic pipe of, for example, stainless.

The first pipe line 50 connects the refrigerant outlet 38 of the heatreceiving head 31 to the refrigerant intake 46 of the heat radiator 32.The first pipe line 50 is extended toward the display supporting portion10 b on the left inside the first housing 4. After a front end of thisfirst pipe line 50 passes through a front face of the display supportingportion 10 b and a front face of the leg portion 23 b on the left, it isintroduced into the display housing 17.

The second pipe line 51 connects the refrigerant intake 37 of the heatreceiving head 31 to the refrigerant outlet 47 of the heat radiator 32.After the second pipe line 51 is introduced to the right side along thefront wall 4 d inside the first housing 4, it is extended toward thedisplay supporting portion 10 a on the right. After a front end of thesecond pipe line 51 passes through a front face of the displaysupporting portion 10 a and a front face of the leg portion 23 a on theright, it is introduced to the leg portion 23 b and then introduced intothe display housing 17.

Therefore, the refrigerant flow paths 36 of the heat receiving head 31is connected to the radiated heat path 45 of the heat radiator 32through the first and second pipe lines 50 and 51. The refrigerant flowpath 36, the radiated heat path 45 and the first/second pipe lines 50and 51 are filled with liquid-like cooling medium like water orfluorocarbon.

As shown in FIGS. 3 and 5, of the first and second pipe lines 50 and 51,portions passing through the leg portions 23 a and 23 b of the displayhousing 17 are composed of an expandable bellows pipe 52 having aflexibility. The bellows pipes 52 are curved in the form of a circlearound the hinge shaft 27 and disposed behind this hinge shaft 27.

Thus, the bellows pipes 52 of the first and second pipe lines 50 and 51are deformable freely in a direction around the hinge shaft 27.Consequently, the first and second pipe lines 50 and 51 are deformedsmoothly following a rotation of the display unit 3 when it is rotatedfrom its closing position to its opening position, so as to absorb acurve applied to the first and second pipe lines 50 and 51 when thedisplay unit 3 is rotated.

As shown in FIG. 1, the display housing 17 has a mounting port 54, whichis open in the rear face 21 thereof. The mounting port 54 is locatedbehind the liquid crystal display panel 18 and has a size fitting to theheat radiator 32. The first heat radiating plate 43 a of the heatradiator 32 has a lower edge portion adjacent the leg portions 23 a and23 b of the display housing 17 and an upper edge portion located on anopposite side to this lower edge portion. A pair of fitting pawls 55 aand 55 b are formed on the upper edge portion of the first heatradiating plate 43 a. These fitting pawls 55 a and 55 b are apart fromeach other in the width direction of the display housing 17.

The heat radiator 32 is fit to the mounting port 54 from the rear face21 of the display housing 17. Consequently, the fitting pawls 55 a and55 b of the heat radiator 32 are hooked on the opening edge portion ofthe mounting port 54 detachably. Further, the first and second heatradiating plates 43 a and 43 b are fixed to an inside face of thedisplay housing 17 through two positions on the lower edge portion withscrews 56. Thus, the heat radiator 32 is maintained such that it is incontact with the inside face of the display housing 17 so that it isthermally connected to the display housing 17.

As shown in FIG. 4, an opposite surface to the second heat radiatingplate 43 b of the first heat radiating plate 43 a of the heat radiator32 is covered with protective layer 57. The protective layer 57 iscomposed of synthetic resin having lower thermal conductivity than thefirst and second heat radiating plates 43 a and 43 b. This protectivelayer 57 is exposed out of the display housing 17 through the mountingport 54 when the heat radiator 32 is fixed to the display housing 17 andfurther, located on the same plane as the rear face 21 of the displayhousing 17.

As shown in FIG. 1, the rear face 21 of the display housing 17 has apair of opening portions 60 a and 60 b at positions corresponding to theleg portions 23 a and 23 b. The opening portions 60 a and 60 b opposethe bellows pipes 52 in the first and second pipe lines 50 and 51. Endsof the opening portions 60 a and 60 b reach the front ends of the legportions 23 a and 23 b while the other ends of the opening portions 60 aand 60 b are continuous to the mounting port 54. Thus, the openingportions 60 a and 60 b are large enough to take out the bellows pipes52.

The opening portions 60 a and 60 b are covered with lids 61 of syntheticresin which can be removed. The lids 61 are fit to the opening portions60 a and 60 b so that the fitting pawl 62 of each end thereof is hookedon the aforementioned heat radiator 32. The other ends of the lids 61are fixed to the front ends of the leg portions 23 a and 23 b through ascrew 63.

Thus, if engagement between the fitting pawl 62 and the heat radiator 32is released by removing the screw 63 as shown in FIG. 7, the lids 61 canbe removed from the display housing 17 so as to open the openingportions 60 a and 60 b. As a result, the bellows pipes 52 insertedinside the leg portions 23 a and 23 b are exposed toward the rear face21 of the display housing 17 through the opening portions 60 a and 60 b.

As shown in FIGS. 3, 11, the aforementioned cooling unit 30 is equippedwith an intermediate cooling unit 70 as intermediate cooling means. Theintermediate cooling unit 70 is located halfway of the first pipe line50 and accommodated inside the first housing 4. The intermediate coolingunit 70 comprises a main body 71 and an electric fan 90.

The main body 71 is composed of metallic material having an excellentthermal conductivity like for example, aluminum alloy and screwed to atop face on the left end portion of the circuit board 11. The main body71 has a first concave portion 72, which is open downward. The openingend of the first concave portion 72 is sealed with a bottom plate 73.The bottom plate 73 forms a refrigerant path 74 in cooperation with thefirst concave portion 72 and this refrigerant path 74 is extended in thedepth direction of the first housing 4.

A pump 76 and an accumulator 77 are built in the main body 71 of theintermediate cooling unit 70 integratedly. A suction end of the pump 76is continuous to the refrigerant outlet 38 of the heat receiving head 31through an upstream portion of the first pipe line 50. A discharge endof the pump 76 is continuous to the refrigerant path 74 through theaccumulator 77. This pump 76 is driven at the same time when theportable computer 1 is powered on and then pressurizes cooling mediumand supplies to the accumulator 77.

As shown in FIG. 11, the accumulator 77 has a pressure accumulatingchamber 78 for accumulating cooling medium discharged from the pump 76.The pressure accumulating chamber 78 is formed on a side portion of themain body 71. Part of the peripheral wall of this pressure accumulatingchamber 78 is constructed of diaphragm 79 elastically deformable. Ifcooling medium discharged from the pump 76 is supplied to the pressureaccumulating chamber 78, the diaphragm 79 is elastically deformedcorresponding to a discharging pressure of the cooling medium so thatthe capacity of the pressure accumulating chamber 78 is changed. As aresult, pulsation of the cooling medium accompanied by driving of thepump 76 is absorbed so as to adjust the discharging pressure of thecooling medium to a constant level. This cooling medium is supplied tothe refrigerant path 74 through a communicating port 80 formed in themain body 71. The refrigerant path 74 communicates with a refrigerantoutlet 81 formed in the main body 71. The refrigerant outlet 81 isconnected to the refrigerant intake 46 of the heat radiator 32 through adownstream portion of the first pipe line 50.

Therefore, cooling medium supplied to the refrigerant path 74 in theintermediate cooling unit 70 from the pump 76 is introduced to the heatradiator 32 through the downstream portion of the first pipe line 50.After this cooling medium flows through the radiated heat path 45 in theheat radiator 32, it is introduced to the heat receiving head 31 throughthe second pipe line 51 and from here, it is returned to an absorptionend of the pump 76 through the upperstream portion of the first pipeline 50. Thus, the cooling medium is forced to circulate between theheat receiving head 31 and the heat radiator 32.

As shown in FIG. 11, the main body 71 has a second concave portion 83,which is open upward. The opening end of the second concave portion 83is sealed with a head plate 84. The head plate 84 forms a cooling airpath 85 in cooperation with the second concave portion 83. The coolingair path 85 adjoins the refrigerant path 74 beyond the main body 71 andis thermally connected to this refrigerant path 74. The cooling air path85 is extended in the width direction of the first housing 4. Thiscooling air path 85 has a cooling air outlet 86. The cooling air outlet86 opposes an exhaust port 87, which is open in the side wall 4 c on theleft side of the first housing 4.

The main body 71 has a plurality of heat radiating fins 88 protrudedfrom a bottom of the second concave portion 83. These heat radiatingfins 88 face the cooling air path 85 such that they are extendedlinearly along the cooling air path 85.

As shown in FIG. 3, the aforementioned electric fan 90 is built in themain body 71 integratedly. The electric fan 90 is located on an oppositeside to the cooling air outlet 86 of the cooling air path 85 so as tofeed cooling air through the cooling air path 85. According to thisembodiment, the electric fan 90 is driven when the temperature of thesemiconductor package 12 and the temperature of the display housing 17arrive at respective predetermined values. Thus, the heat receiving head31 thermally connected to the semiconductor package 12 and the heatradiator 32 are equipped with temperature sensors 91 a and 91 brespectively. The electric fan 90 is driven according to temperaturesignals from the temperature sensors 91 a and 91 b.

Next, a cooling operation of the semiconductor package 12 will bedescribed with reference to FIG. 12.

As shown in FIG. 12, power of the portable computer 1 is turned on instep S1. Consequently, in step S2, the pump 76 of the cooling unit 30 isdriven so that circulation of the cooling medium between the heatreceiving head 31 and the heat radiator 32 is started.

If the IC chip 14 of the semiconductor package 12 is heated during anoperation of the portable computer 1, heat of the IC chip 14 istransmitted to the heat transmitting case 34 of the heat receiving head31. Heat of the IC chip 14 transmitted to the heat transmitting case 34is transferred to cooling medium flowing through the refrigerant flowpaths 36. After heat exchange at the heat receiving head 31, heatedcooling medium is introduced to the heat radiator 32 through theupstream portion of the first pipe line 50, the refrigerant path 74 inthe intermediate cooling unit 70 and the downstream portion of the firstpipe line 50. Thus, heat of the IC chip 14 is transferred to the heatradiator 32 through a flow of the cooling medium.

The cooling medium introduced to the heat radiator 32 flows through themeandering radiated heat path 45. In this flow process, heat absorbed inthe cooling medium is transmitted to the first and second heat radiatingplates 43 a and 43 b. Part of heat transmitted to the first and secondheat radiating plates 43 a and 43 b is diffused by heat transfer to thedisplay housing 17 so that it is discharged into the atmosphere from thesurface of the display housing 17.

The protective layer 57 covering the first heat radiating plate 43 a isexposed out of the display housing 17 through the mounting port 54 inthe rear face 21 of the display housing 17. Therefore, most of heattransmitted to the first heat radiating plate 43 a is discharged intothe atmosphere from the surface of the protective layer 57.

Cooling medium cooled by heat exchange by means of the heat radiator 32is returned to the absorbing end of the pump 76 through the second pipeline 52. After this cooling medium is pressurized by the pump 76, it issupplied to the refrigerant flow paths 36 of the heat receiving head 31through the accumulator 77.

While the portable computer 1 remains powered on, the temperatures ofthe semiconductor package 12 and the display housing 17 are monitored bythe temperature sensors 91 a and 91 b. Thus, as long as the portablecomputer 1 is powered on, in step S3, the temperature of thesemiconductor package 12 is being checked.. When the temperature of thissemiconductor package 12 reaches a predetermined level, the processingproceeds to step S4, in which the electric fan 90 of the intermediatecooling unit 70 is started.

If the electric fan 90 is driven, air inside the first housing 4 isturned to cooling air and then fed to the cooling air path 85. Becausethe cooling air path 85 is thermally connected to the refrigerant path74, part of heat in the cooling medium flowing through this refrigerantpath 74 is taken away by flow of cooling air flowing through the coolingair path 85 and discharged out of the first housing 4 through theexhaust port 87. Thus, the cooling medium heated by the heat receivinghead 31 is cooled before it reaches the heat radiator 32, thereby thetemperature of the cooling medium fed to the heat radiator 32 being keptlow.

Unless the temperature of the semiconductor package 12 checked in stepS3 reaches the predetermined value, the processing proceeds to step S5,in which the temperature of the display housing 17 is checked. Becausethe pump 76 of the intermediate cooling unit 70 continues to be drivenas long as the portable computer 1 remains powered on, the coolingmedium continues to transfer heat of the semiconductor package 12 to thedisplay housing 17. Thus, even if the temperature of the semiconductorpackage 12 does not reach the predetermined value, when the temperatureof the display housing 17 reaches the predetermined value, theprocessing proceeds to step S4, in which the electric fan 90 is started.

Consequently, part of heat in the cooling medium flowing through therefrigerant path 74 is taken away by a flow of cooling air flowingthrough the cooling air path 85. As a result, the temperature of coolingmedium fed to the heat radiator 32 drops, so that the amount of heattransferred from the heat radiator 32 to the display housing 17decreases.

After the driving of the electric fan 90 is started also, thetemperatures of the semiconductor package 12 and the display housing 17continue to be checked in steps S6, S7. Here, if it is determined thatthe temperatures of the semiconductor package 12 and the display housing17 are over the predetermined value, the processing proceeds to step S8.In step S8, processing speed of the semiconductor package 12 is reducedtemporarily so as to reduce power consumption of the semiconductorpackage 12 thereby suppressing generation of heat in the IC chip 14.

According to such a portable computer 1, cooling medium is forced tocirculate between the heat receiving head 31 and the heat radiator 32 soas to transfer heat of the semiconductor package 12 to the displayhousing 17 effectively and discharge it into the atmosphere. Therefore,as compared to the conventional ordinary forced air cooling system, heatradiation of the semiconductor package 12 can be raised thereby makingit possible to correspond to increase of generation of heat reasonably.

Further, according to the above-described structure, the cooling mediumheated by the heat receiving head 31 is cooled through the intermediatecooling unit 70 before it reaches the heat radiator 32. Thus, thetemperature of the cooling medium fed to the heat radiator 32 can belowered so that a rise of the surface temperature of the display housing17 receiving heat of the heat radiator 32 can be suppressed. Thus, if anoperator touch the surface of the display housing 17 with his hand whenfor example, adjusting the standing angle of the display unit 3 orcarrying the portable computer 1, he never feels a sudden of heat,thereby making it possible to lower a thermal influence of the portablecomputer 1 upon the human body during use.

At the same time when the portable computer 1 is powered on, circulationof cooling medium is started so as to transfer heat of the semiconductorpackage 12 to the heat radiator 32. Thus, at the time of low/medium loadin which the temperature of the semiconductor package 12 is not raisedso much, it is possible to stop operation of the electric fan 90 orsuppress the rotation speed, thereby enabling a silent operation.

Further, because the pump 76 and the accumulator 77 are built in themain body 71 of the intermediate cooling unit 70, a structure containinga movable portion can be handled as a single unit. Thus, incorporationof the cooling unit 30 into the first housing 4 can be facilitated,thereby improving operation efficiency of assembly of the portablecomputer 1.

Additionally, the first pipe line 50 for introducing cooling mediumheated by the heat receiving head 31 to the heat radiator 32 and thesecond pipe line 51 for returning cooling medium cooled by the heatradiator 32 to the heat receiving head 31 are disposed on the left andright leg portions 23 a and 23 b of the display housing 17. Thus, atportions where the first and second pipe lines 50 and 51 are stretchedbetween the first housing 4 and the display housing 17, these first andsecond pipe lines 50 and 51 can be kept apart from each other so as toseparate them thermally. Thus, it is possible to prevent an undesiredheat exchange between the first pipe line 50 and the second pipe line51, thereby raising heat transfer efficiency from the heat receivinghead 31 to the heat radiator 32.

On the other hand, a procedure for removing the display unit 3 from thefirst housing 4 in the portable computer 1 having the above-describedstructure will be described.

First, as shown in FIG. 6, the display unit 3 is rotated to the closingposition, so that the screws 63 which fix the lids 61 are exposedrearward of the display supporting portions 10 a and 10 b. Next, thescrews 63 are loosened so as to release fixing of the lids 61 with thesescrews 63. After that, engagement between the fitting pawl 62 and theheat radiator 32 is released and the lids 61 are removed from thedisplay housing 17. Consequently, as shown in FIG. 7, the openingportions 60 a and 60 b are opened so that the bellows pipes 52 insertedinside the leg portions 23 a and 23 b are exposed toward the rear face21 of the display housing 17 through the opening portions 60 a and 60 b.

Next, the screws 56 which fix the first and second heat radiating plates43 a and 43 b to the display housing 17 are loosened so as to releaseengagement between the heat radiator 32 and the display housing 17.Subsequently, the fitting pawls 55 a and 55 b of the heat radiator 32are separated from the opening edge portion of the mounting port 54 andthen, this heat radiator 32 is taken out in the direction of the rearface 21 of the display housing 17 through the mounting port 54. Thisprocedure for taking out this heat radiator 32 can be carried outirrespective of whether the display unit 3 is rotated to its closingposition or the opening position.

Because the opening portions 60 a and 60 b are continuous to themounting port 54, the first and second pipe lines 50 and 51 continuousto this heat radiator 32 are pulled out of the opening portions 60 a and60 b rearward of the leg portions 23 a and 23 b at the same time whenthe heat radiator 32 is taken out of the mounting port 54. Because atthis time, the second pipe line 51 is disposed behind the hinge shaft27, the hinge shaft 27 never becomes an obstacle when taking the secondpipe 51 out of the leg portion 23 a.

Thus, with the first and second pipe lines 50 and 51 connected to theheat radiator 32 as shown in FIG. 13, the heat radiator 32 can be pulledout rearward of the display housing 17.

Next, by taking the top cover 6 of the first housing 4 out of the base5, the first bracket 25 of the hinge device 24 fixed to this base 5 isexposed. Finally, the fixing between the first bracket 25 and the bossportion 28 with the screws is released and the display unit 3 is takenout upward of the base 5 together with the hinge device 24. Thus, thedisplay unit 3 and the computer main body 2 can be separated from eachother.

When mounting the display unit 3 onto the computer main body 2, thefirst bracket 25 of the hinge device 24 is screwed to the boss portion28 of the base 5 before the top cover 6 is mounted on the base 5. Afterthat, the top cover 6 is mounted on the base 5 so as to cover the firstbracket 25 with this top cover 6.

Next, the heat radiator 32 is fitted with the mounting port 54 in therear face 21 of the display housing 17, so that the fitting pawls 55 aand 55 b of the first heat radiating plate 43 a are hooked on theopening edge portion of the mounting port 54. Further, the lower edgeportions of the first and second heat radiating plates 43 a and 43 b arefixed to the display housing 17 with the screws 56. Subsequently, thefirst and second pipe lines 50 and 51 continuous to the heat radiator 32are inserted inside the leg portions 23 a and 23 b through the openingportions 60 a and 60 b.

Finally, the lids 61 are fitted with the opening portions 60 a and 60 band these lids 61 are fixed to the leg portions 23 a and 23 b with thescrews 63. Consequently, the computer main body 2 and the display unit 3are coupled with each other rotatably, so that the incorporation of theheat radiator 32 in the display housing 17 is completed.

With such a structure, the heat radiator 32 accommodated in the displayhousing 17 can be taken out of the rear face 21 of the display housing17 together with the first and second pipe lines 50 and 51. Thus, withthe heat radiator 32 taken out of the display housing 17, the displayunit 3 can be taken out of the first housing 4 or installed to the firsthousing 4.

Therefore, when attaching/detaching the display unit 3 to/from the firsthousing 4, it is not necessary to release thermal connection between theheat receiving head 31 and the semiconductor package 12 or thermallyconnect again, so that the procedure for disassembly/assembly of thethermally connecting portion between the heat receiving head 31 and thesemiconductor package 12 is not required.

Thus, no unreasonable force is applied to the precision semiconductorpackage 12 or the positional relationship between the semiconductorpackage 12 and the heat receiving head 31 is not changed, so thatreliability of heat conduction can be maintained favorably.

Further, the bellows pipe 52 in the second pipe line 51 is disposedbehind the hinge shaft 27 inside the leg portion 23 a. Thus, thecurvature of the bellows pipe 52 when the display unit 3 is rotated tothe closing position can be suppressed to be small as shown in FIG. 5.As a result, when the display unit 3 is rotated, an unreasonable bendingforce is not applied to the bellows pipe 52 thereby improving thedurability of the bellows pipe 52.

Meanwhile, according to the first embodiment, when the temperature ofthe semiconductor package and the temperature of the display housingreach their predetermined values, the electric fan is started. However,the present invention is not restricted to this. For example, it ispermissible to adjust the air amount of the cooling air or the flowamount of the cooling medium according to a temperature signal outputtedfrom the temperature sensor.

Further, the pump and accumulator do not always have to be builttogether with the intermediate cooling unit and the pump and accumulatormay be installed halfway of the second pipe line. Because with thisstructure, cooling medium cooled by the radiator is introduced to thepump and accumulator, thermal influence upon the pump and accumulatorcan be suppressed thereby improving the reliability of the operation.

The present invention is not restricted to the above-described firstembodiment. A second embodiment of the present invention shown in FIG.14 will be described.

The second embodiment is different from the first embodiment in that thelids 61 which cover the opening portions 60 a and 60 b in the legportions 23 a and 23 b are connected to each other through a connectingpanel 100. Other basic structure of the portable computer 1 is the sameas the first embodiment.

The connecting panel 100 is an elongated plate extending in the widthdirection of the display housing 17. The connecting panel 100 is fitteddetachably in an end portion adjacent the leg portions 23 a and 23 b ofthe mounting port 54 of the display housing 17 and functions as a coverportion for covering this mounting port 54 partially. This connectingpanel 100 is located on the same plane as the rear face 21 of thedisplay housing 17 and the protective layer 57 of the heat radiator 32.

FIG. 15 shows a third embodiment of the present invention.

This third embodiment is a further development of the second embodiment.According to the third embodiment, a connecting panel 110 for connectingthe lids 61 is large enough to cover the mounting port 54 entirely. Theconnecting panel 110 is fit to the mounting port 54 detachably such thatit is overlaid on the first heat radiating plate 43 a of the heatradiator 32 supported by the display housing 17. Thus, the first heatradiating plate 43 a of the heat radiator 32 is not equipped with anyprotective layer like shown in the first embodiment and this connectingpanel 110 functions a protective layer which covers the first heatradiating plate 43 a.

Further, FIGS. 16-18 show a fourth embodiment of the present invention.

According to the fourth embodiment, the structure of a cooling unit 120for cooling mainly the semiconductor package 12 is different from thatof the first embodiment and other basic structure of the portablecomputer 1 is the same as the first embodiment. Thus, for the fourthembodiment, like reference numerals are attached to the same componentas the first embodiment and a description thereof is omitted.

As shown in FIG. 16, the convex portion 8 located at the rear endportion of the first housing 4 is so constructed that both ends thereofare located inside in the width direction of the first housing 4 withrespect to the side wall 4 c of the first housing 4. At the rear endportion of the first housing 4 are formed a pair of display supportingportions 121 a and 121 b which are specified by both end faces of theconvex portion 8 and a top face of the upper wall 4 b.

The leg portions 23 a and 23 b of the display housing 17 are introducedto the display supporting portions 121 a and 121 b. These leg portions23 a and 23 b have side faces opposing both end faces of the convexportion 8.

The hinge shaft 27 of the hinge device 24 is extended horizontally suchthat it passes through the right end face of the convex portion 8 andthe right side face of the leg portion 23 a. The leg portion 23 blocated on the left opposite to the hinge device 24 has a cylindricalguide 122 protruded from a side face thereof toward the left end face ofthe convex portion 8. The guide 122 passes through the left end face ofthe convex portion 8 rotatably such that it is open inside the convexportion 8. Thus, the inside of the first housing 4 and the inside of thedisplay housing 17 communicate with each other through the guide 122 andthe left leg portion 23 b.

The cooling unit 120 for cooling the semiconductor package 12 comprisesa heat receiving head 31 accommodated inside the first housing 4, a heatradiator 123 accommodated inside the display housing 17 and acirculating path 124 for connecting the heat receiving head 31 and theheat radiator 123.

The heat radiator 123 has a flat heat radiating plate 125 and ameanderingly bent heat radiating pipe 126. The heat radiating plate 125is composed of, for example, metallic material having excellent heatconductivity like aluminum alloy. The heat radiating plate 125 is fixedto an inside face of the display housing 17 behind the liquid crystaldisplay panel 18 with fixing means such as screws, adhesive agent andthe like, so that it is thermally connected to the display housing 17.

The heat radiating pipe 126 is composed of aluminum alloy or copper basemetallic material having an excellent heat conductivity. The heatradiating pipe 126 is fixed to the heat radiating plate 125 by bondingor soldering means so that it is thermally connected to this heatradiating plate 126. The heat radiating pipe 126 is equipped with arefrigerant intake 127 and a refrigerant outlet 128. The refrigerantintake 127 and the refrigerant outlet 128 are located at the left endportion of the heat radiator 123.

The circulating path 124 includes a first pipe line 130 and a secondpipe line 131. These pipe lines 130 and 131 are composed of flexiblematerial like silicone resin, for example. The first pipe line 130 isintended for connecting the refrigerant outlet 38 of the heat receivinghead 31 to the refrigerant intake 127 of the heat radiating pipe 126.After introduced to the left end portion of the convex portion 8 insidethe first housing 4, this first pipe line 130 is introduced into thedisplay housing 17 through the guide 122 and the inside of the legportion 23 b on the left. The second pipe line 131 is intended forconnecting the refrigerant outlet 128 of the heat radiating pipe 126 tothe refrigerant intake 37 of the heat receiving head 31. Afterintroduced to the left end portion of the convex portion 8 inside thefirst housing 4, the second pipe line 131 is introduced to the inside ofthe display housing 17 through the guide 122 and the leg portion 23 b onthe left side.

Thus, the refrigerant flow paths 36 of the heat receiving head 31 isconnected to the heat radiating pipe 126 of the heat radiator 123through the first and second pipe lines 130 and 131. The refrigerantflow paths 36, the heat radiating pipe 126 and the first/second pipelines 130 and 131 are filled with liquid-like cooling medium.

A pump 132 is installed halfway of the second pipe line 131. When thepower of the portable computer 1 is turned on, the pump 132 is startedso as to send out cooling medium to the heat receiving head 31. As aresult, the cooling medium is introduced to the heat radiator 123 fromthe heat receiving head 31 through the first pipe line 130 and afterflowing through the heat radiating pipe 126 in this heat radiator 132,returned to the pump 132 through the second pipe line 131.

As shown in FIG. 16, the first and second pipe lines 130 and 131 haveintermediate portions 133 a and 133 b. The intermediate portions 133 aand 133 b exist between the convex portion 8 and the leg portion 23 b ofthe display housing 17. The intermediate portions 133 a and 133 b areextended horizontally along the axis X1 of the hinge shaft 27 such thatthey are disposed in parallel to each other with a gap therebetween.

The intermediate portions 133 a and 133 b of the first and second pipes130 and 131 are provided with a holder 134 for keeping constant the gapbetween these intermediate portions 133 a and 133 b. The holder 134 iscomposed of material hard to transmit heat. As shown in FIG. 17, theholder 134 has a first support pipe 135 a and a second support pipe 135b. The first support pipe 135 a supports the intermediate portion 133 aof the first pipe line 130 rotatably in an axial direction. The secondsupport pipe 135 b supports the intermediate portion 133 b of the secondpipe line 131 rotatably in an axial direction.

The first and second support pipes 135 a and 135 b are linked through apair of columns 136. The columns 136 are extended in the diameterdirection of the first and second support pipes 135 a and 135 b suchthat they are disposed between both end portions of these support pipes135 a and 135 b. Thus, the first and second support pipes 135 a and 135b are disposed in parallel to each other across a heat insulating gap137.

As shown in FIG. 16, the first and second pipe lines 130 and 131 aredivided to upstream portions 130 a and 131 a and downstream portions 130b and 131 b inside the first housing 4. These upstream portions 130 aand 131 a and the downstream portions 130 b and 131 b are joineddetachably through a joint 140. As shown in FIGS. 18A and 18B, the joint140 has a first joint portion 141 and a second joint portion 142. Thefirst joint portion 141 is connected to the downstream portion 130 b ofthe first pipe line 130 and the upstream portion 131 a of the secondpipe line 131. The second pipe portion 142 is connected to the upstreamportion 130 a of the first pipe line 130 and the downstream portion 131b of the second pipe line 131.

The first joint portion 141 has a hollow cylindrical body 145. A pair ofrefrigerant flow paths 146 are formed inside the body 145. Therefrigerant flow paths 146 are connected to the downstream portion 130 bof the first pipe line 130 and the upstream portion 131 a of the secondpipe line 131. Each of the refrigerant flow paths 146 has a valve hole147 which is open to an end of the body 145. A pair of pressing rods 148protruding from the body 145 through an opening edge portion of thevalve hole 147 are provided at a front end of the body 145.

A ball-like valve body 149 is accommodated in each refrigerant flow path146 and used as a closing means. The valve body 149 is supported by thebody 145 and can approach and leaves the valve hole 147, always pressedtoward the valve hole 147 by a spring 150. Thus, when the first jointportion 141 is separated from the second joint portion 142, the valvebody 149 remains in firm contact with the opening edge portion of thevalve hole 147, closing the valve hole 147.

The second joint portion 142 has a hollow cylindrical body 152. A pairof refrigerant flow paths 153 are formed inside the body 152. Therefrigerant flow paths 153 are connected to the upstream portion 130 aof the first pipe line 130 and the downstream portion 131 b of thesecond pipe line 131. Each of the refrigerant flow paths 153 has afitting hole 154, which is open to a front end of the body 152. The body145 of the first joint portion 141 removably secured to the fitting hole154 detachably.

As shown in FIG. 18B, a pressing protrusion 155 and a partition wall 157having a valve hole 156 are provided in the middle part of therefrigerant flow path 153. The protrusion 155 extends toward the fittinghole 154. The partition wall 157 opposes the fitting hole 154 across thepressing protrusion 155. A ball-like valve body 158 is accommodated as aclosing means between the partition wall 157 and the other end of therefrigerant flow path 153. The valve body 158 is supported by the body152 and can approach and leave the valve hole 156 and is always pressedtoward the valve hole 156 by a spring 159. Thus, while the first jointportion 141 is separated from the second joint portion 142, the valvebody 158 remains in firm contact with the opening edge portion of thevalve body 156, closing the valve hole 156.

When as shown in FIG. 18A, the body 145 of the first joint portion 141is fit to the fitting holes 154 in the second joint portion 142, thepressing protrusions 155 of the second joint portion 142 enter the valveholes 147 in the first joint portion 141.

The protrusions 155 strike the valve bodies 149. Consequently, the valvebodies 149 are pushed and leave the opening edge portions of the valveholes 147, in spite of the force of the springs 150. The valve hole 147are thereby opened.

At the same time, the pressing rods 148 of the body 145 passes over theperiphery of the pressing protrusions 155 and enter the valve holes 156in the joint portion 142. The rods 148 strike the valve bodies 158. As aresult, the valve bodies 158 are pushed and leave the opening edgeportion of the valve holes 156, against the force of the springs 159.The valve holes 156 are thereby opened.

Since the first joint portion 141 is connect with the second jointportion 142, the refrigerant flow paths 146 and 153 communicate witheach other through the valve holes 147 and 156.

When the first joint portion 141 is separated from the second jointportion 142 as shown in FIG. 18B, the valve bodies 149 are no longerpressed by the pressing protrusions 155. At the same time, the valvebodies 158 are no longer pressed by the pressing rods 148. Thus, thevalve bodies 149 and 158 are pressed against the opening edge portionsof the valve holes 147 and 156 by the springs 150 and 159. The bodies149 and 158 seal the valve holes 147 and 156. Thus, the refrigerant flowpaths 146 and 153 continuous to the first and second pipe lines 130 and131 are automatically closed, thereby preventing a leakage of thecooling medium.

If the IC chip 14 of the semiconductor package 12 is heated in theportable computer 1 having such a structure, heat of the IC chip 14 istransmitted to the heat transmitting case 34 of the heat receiving head31. Because the cooling medium is supplied to the refrigerant flow paths36 of this heat transmitting case 34, heat transmitted to the heattransmitting case 34 is transferred to the cooling medium flowingthrough the refrigerant flow paths 36 from the heat transmitting case34. After heated by heat exchange by means of this heat receiving head31, the cooling medium is introduced to the heat radiator 123 of thedisplay unit 3 through the first pipe line 130, so that heat of the ICchip 14 is transferred to the heat radiator 123 through a flow of thecooling medium.

The cooling medium introduced to the heat radiator 123 flows along themeandering heat radiating pipe 126. In this flow process, heat absorbedin the cooling medium is transmitted to the heat radiating pipe 126 anddiffused by heat conductivity to the heat radiating plate 125. Becausethe heat radiating plate 125 is thermally connected to the displayhousing 17, heat transferred to the heat radiating plate 125 is diffusedby heat conductivity to the display housing 17 and then, discharged intothe atmosphere from the surface of the display housing 17.

The cooling medium cooled by heat exchange by means of the heatradiating pipe 126 is returned to the pump 132 through the second pipeline 131 and after pressurized by this pump 132, supplied to the heatreceiving head 31.

The first pipe line 130 in which the cooling medium heated by heatexchange by means of the heat receiving head 31 flows and the secondpipe line 131 in which the cooling medium cooled by heat exchange bymeans of the heat radiator 123 extend between the first housing 4 andthe display housing 17. Then, the intermediate portion 133 a of thefirst pipe line 130 and the intermediate portion 133 b of the secondpipe line 131 are held by the first and second support pipes 135 a and135 b in the holder 134. Consequently, the gap between the first pipeline 130 and the second pipe line 131 is maintained constant and the gapbetween the first pipe line 130 and the second pipe line 131 isthermally shut down by the gap 137 between the first and second supportpipe lines 135 a and 135 b.

Thus, although the first pipe line 130 in which the heated coolingmedium flows and the second pipe line 131 in which the cooled coolingmedium flows pass inside the guide 122 such that they adjoin each other,a undesired heat exchange between the adjacent pipe lines 130 and 131can be prevented. Therefore, transmission efficiency of heat from theheat receiving head 31 to the heat radiator 123 can be raised, therebymaintaining heat radiation performance of the semiconductor package 12.

On the other hand, a procedure for taking the display unit 3 out of thefirst housing 4 in the portable computer 1 having such a structure willbe described. First, the top cover 6 of the first housing 4 is removedfrom the base 5 so as to expose the first and second pipe lines 130 and131 and the joint 140 accommodated in the first housing 4.

Next, the first joint portion 141 and the second joint portion 142 ofthe joint 140 are separated from each other and the first and secondpipe lines 130 and 131 are divided to the upstream portions 130 a and131 a and the downstream portions 130 b and 131 b inside the firsthousing 4. Consequently, the circulating path 124 is divided between thefirst housing 4 and the display unit 3. Thus, with the heat receivinghead 31 remaining in the first housing 4, the display unit 3 can beremoved from the first housing 4 or can be installed onto the firsthousing 4.

For the reason, when attaching or detaching the display unit 3 to/fromthe first housing 4, it is not necessary to release thermal connectionbetween the heat receiving head 31 and the semiconductor package 12 orthermally connect again, so that the procedure for disassembly/assemblyof the thermal connecting portion between the heat receiving head 31 andthe semiconductor package 12 is not required. Therefore, no unreasonableforce is applied to the precision semiconductor package 12 and thepositional relationship between the semiconductor package 12 and theheat receiving head 31 is not changed, thereby maintaining reliabilityof heat transfer favorably.

Further, if the first joint portion 141 is separated from the secondjoint portion 142, the valve holes 147 and 156 in the respective jointportions 141 and 142 are automatically shut down by the valve bodies149, 158. Thus, a leakage of the cooling medium can be prevented and anyspecial procedure for sealing a dividing portion between the first andsecond pipe lines 130 and 131 is not required.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A cooling unit for use in an electronic apparatushaving a computer main body containing a heat generating component and adisplay unit supported by said computer main body, said cooling unitcomprising: a heat receiving portion thermally connected to said heatgenerating component and accommodated in said computer main body; a heatexchanging portion installed on said display unit; circulating means forcirculating cooling medium between said heat receiving portion and saidheat exchanging portion, said circulating means having a pipe line forintroducing cooling medium heated by said heat receiving portion to saidheat exchanging portion; and intermediate cooling means installed insaid pipe line, said intermediate cooling means forcing the heatedcooling medium flowing from said heat receiving portion to said heatexchanging portion to be cooled.
 2. A cooling unit according to claim 1,wherein said intermediate cooling means comprises a main body having apath in which the heated cooling medium flows and a fan for supplyingcooling air to said main body.
 3. A cooling unit according to claim 2,wherein said main body comprises a cooling air path in which saidcooling air flows and a plurality of heat radiating fins exposed on saidcooling air path, said cooling air path being thermally connected tosaid path.
 4. A cooling unit according to claim 2, wherein saidcirculating means includes a pump for forcing the cooling medium to becirculated between said heat receiving portion and said heat exchangingportion and an accumulator for absorbing a pulsation of the coolingmedium discharged from said pump.
 5. A cooling unit according to claim4, wherein said pump and said accumulator are incorporated in said mainbody integrally.
 6. An electronic apparatus comprising: a housingcontaining a heat generating component; a display unit supported by saidhousing; a heat receiving portion accommodated in said housing andthermally connected to said heat generating component; a heat exchangingportion installed on said display unit; circulating means forcirculating cooling medium between said heat receiving portion and saidheat exchanging portion, said circulating means being disposedthroughout said housing and said display unit and having a pipe line forintroducing cooling medium heated by said heat receiving portion to saidheat exchanging portion; and intermediate cooling means installed insaid pipe line of said circulating means, said intermediate coolingmeans forcing the heated cooling medium flowing from said heat receivingportion to said heat exchanging portion to be cooled.
 7. An electronicapparatus according to claim 6, wherein said display unit contains adisplay housing incorporating the display panel, said heat exchangingportion has thermally conductive heat radiating plates supported by saiddisplay housing, said heat radiating plates being provided with heatradiating path for introducing the heated cooling medium.
 8. Anelectronic apparatus according to claim 6, wherein said circulatingmeans includes a pump for forcing said cooling medium to be circulatedbetween said heat receiving portion and said heat exchanging portion andsaid intermediate cooling means contains a main body having a path inwhich the heated cooling medium flows and a fan for supplying coolingair to said main body.
 9. An electronic apparatus according to claim 8,wherein the pump of said circulating means is driven when the power ofsaid electronic apparatus is turned on and said fan is driven when thetemperature of said heat generating component reaches a predeterminedvalue.
 10. An electronic apparatus according to claim 9, wherein saidfan is driven when the temperature of said display unit reaches apredetermined value.
 11. An electronic apparatus comprising: a firsthousing containing a heat generating component; a second housing, saidsecond housing being journaled detachably on a rear end of said firsthousing through a hinge device having a hinge shaft extending in thewidth direction of said first housing and having a rear face which isdirected backward of said first housing when said second housing isrotated to a posture in which it stands up from the rear end of saidfirst housing; a heat receiving portion accommodated inside said firsthousing and thermally connected to said heat generating component; aheat exchanging portion installed on said second housing, said heatexchanging portion being capable of being taken out of said rear face;and circulating means for circulating the cooling medium between saidheat receiving portion and said heat exchanging portion, saidcirculating means comprising a first pipe line for introducing coolingmedium heated by said heat receiving portion to said heat exchangingportion and a second pipe line for introducing cooling medium cooled byheat exchange by means of said heat exchanging portion to said heatreceiving portion, said first and second pipe lines being disposedthroughout the inside of said first housing and the inside of saidsecond housing via backward of said hinge shaft, said rear face of saidsecond housing having at least an opening portion at a positioncorresponding to said first and second pipe lines, said opening portionbeing covered with a removable lid.
 12. An electronic apparatusaccording to claim 11, wherein at least a portion passing behind thehinge shaft, of each of said first and second pipe lines hasflexibility.
 13. An electronic apparatus according to claim 11, whereinportions extending between said first housing and said second housing ofsaid first and second pipe lines are disposed apart from each other inthe width direction of the housings.
 14. An electronic apparatusaccording to claim 12, wherein said heat exchanging portion containsthermally conductive heat radiating plates having a heat radiating pathfor introducing the heated cooling medium and said second housingcontains a mounting hole in which said heat radiating plates are to beembedded in a rear face thereof, said mounting hole being continuous tosaid opening portions.
 15. An electronic apparatus according to claim14, wherein a face on an opposite side to said heat radiating path, ofsaid heat radiating plate is covered with a protective layer having alower heat conductivity than the heat radiating plate and saidprotective layer is exposed out of said second housing through saidmounting hole.
 16. An electronic apparatus according to claim 14,wherein said lid is provided integrally with a cover portion forcovering said heat radiating plate, said cover portion being fit in saidmounting hole detachably.
 17. An electronic apparatus according to claim11, further comprising intermediate cooling means installed halfway ofsaid first pipe line, said intermediate cooling means forcing heatedcooling medium flowing from said heat receiving portion to said heatexchanging portion to be cooled.
 18. An electronic apparatus comprising:a housing accommodating a heat generating component and being capable ofbeing opened upward; a display unit supported by said housing; a heatreceiving portion accommodated in said housing and thermally connectedto said heat generating component; a heat exchanging portion installedon said display unit; and circulating means for circulating coolingmedium between said heat receiving portion and said heat exchangingportion, said circulating means comprising a first pipe line forintroducing cooling medium heated by said heat receiving portion to saidheat exchanging portion and a second pipe line for introducing coolingmedium cooled by heat exchange by means of said heat exchanging portionto said heat receiving portion, said first and second pipe lines beingdisposed throughout the inside of said housing and the inside of saiddisplay unit and being divided to upstream portions and downstreamportions inside said housing, said upstream portions and said downstreamportions being connected detachably through a joint, said joint havingclosing means for closing said first and second pipe lines when saidfirst and second pipe lines are divided to the upstream portions and thedownstream portions.
 19. An electronic apparatus according to claim 18,wherein said display unit has a pair of leg portions disposed apart fromeach other in the width direction thereof, said leg portions beingsupported rotatably by said housing.
 20. An electronic apparatusaccording to claim 19, wherein said first and second pipe lines areplaced through the inside of at least any one of said leg portions andthermally insulated from each other inside said leg portions.